Every equinox this Maya pyramid puts on a spooky ancient light show.

No telescopes, no power, no gift shop: The Observatory of Chichen Itza, one of the world's oldest observatories, takes astronomy back to basics.

The world's only museum devoted solely to the art and collection of action figures.

The largest land animal skull ever discovered.

Twenty-year effort to raise a castle using tools and techniques from the 13th century is now abandoned in the Arkansas woods.

Where hills of dirt conceal the burial ground of one of the most powerful ancient Native American societies.

A spring-fed pool so deep it's used for scuba diving as well as swimming.

A popular swimming hole that hides one of America's most deadly diving spots.

An emerald-green grotto just a short trip from Austin.

The second-largest cave chamber in the world was discovered in 1898 by a 16-year-old and a friend known as "Pothead."

Visitors can walk over the largest concentration of Columbian mammoths to have died from one event.

Tracks near this Texas nature site were once thought to support the Creationist belief that man and dino coexisted.